The position formatting of a character string with reference to a fixed position such as a left margin in a line oriented soft copy (display) or hard copy (printer) output involves recursive formatting. Thus, the first character is formatted with respect to the margin and subsequent characters are aligned to the previous aligned characters in the character string. In the cursored electronic display of text character strings, it is known to use a horizontal scale line (tab rack) across the display upon which can be registered tab stops. A tab character in the text character string is a formatting control which tells the system to interrogate the tab rack, and if there is a tab stop, the system formats the next text character at the position following the tab character. Consequently, a left margin will have its position indicated by a tab stop along the left end of the scale line. The first tab character in the text stream will be formatted with respect thereto.
A multitext column table has each column position tab stopped along the scale line. The intercolumn intervals are filled with space characters. A multicolumn table consists of multiple horizontal lines or rows. The column entries for each row include a tab character followed by one or more text characters. Each tab character causes the system to look to the next consecutive tab stop to define the position for the immediately appended text characters to be positioned on the display as the counterpart column entry. Suppose, a new column having one or more null-entries is inserted between a pair of adjacent columns. Upon building the table a row at a time while executing this copy/insertion function, the system will fail to recognize the null-entry and will proceed to insert the next tab and text of first right adjacent column having a text entry and write it into the null-entry position of the inserted column for that row. This phenomenon is termed "migration" or "interleaving". A parallel problem arises when a column of text characters is to be inserted between a pair of columns having at least one null-entry counterpart left adjacent to the text entry of the inserted column on the same row. Here, the text column entry will migrate to the "hole" no-entry counterpart in the same row of any left adjacent column. Further, a veritable collapse or "cave-in" may occur where inserted or copied columns are longer than or shorter than other columns in the table.
Prior art word processing systems attempted to control the migration or collapse of column entries and columns by establishing a keying rule that the operator would follow. This meant that the operator had to remember to type extra tabs at the end of any line that did not contained the specific entry for every column. This would wreak havoc in an actual bulk transcription.